Linux Fu: The Great Power Of Make

June 22, 2018 by Al Williams 76 Comments

Over the years, Linux (well, the operating system that is commonly known as Linux which is the Linux kernel and the GNU tools) has become much more complicated than its Unix roots. That’s inevitable, of course. However, it means old-timers get to slowly grow into new features while new people have to learn all in one gulp. A good example of this is how software is typically built on a Linux system. Fundamentally, most projects use make — a program that tries to be smart about running compiles. This was especially important when your 100 MHz CPU connected to a very slow disk drive would take a day to build a significant piece of software. On the face of it, make is pretty simple. But today, looking at a typical makefile will give you a headache, and many projects use an abstraction over make that further obscures things.

In this article, I want to show you how simple a makefile can be. If you can build a simple makefile, you’ll find they have more uses than you might think. I’m going to focus on C, but only because that’s sort of the least common denominator. A make file can build just about anything from a shell prompt.

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Federico Faggin: The Real Silicon Man

June 19, 2018 by Steven Dufresne 47 Comments

While doing research for our articles about inventing the integrated circuit, the calculator, and the microprocessor, one name kept popping which was new to me, Federico Faggin. Yet this was a name I should have known just as well as his famous contemporaries Kilby, Noyce, and Moore.

Faggin seems to have been at the heart of many of the early advances in microprocessors. He played a big part in the development of MOS processors during the transition from TTL to CMOS. He was co-creator of the first commercially available processor, the 4004, as well as the 8080. And he was a co-founder of Zilog, which brought out the much-loved Z80 CPU. From there he moved on to neural networking chips, image sensors, and is active today in the scientific study of consciousness. It’s time then that we had a closer look at a man who’s very core must surely be made of silicon.

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Lawn From Hell Saved By Mower From Heaven

June 19, 2018 by Kristina Panos 94 Comments

It’s that time of year again, at least in the northern hemisphere. Everything is alive and growing, especially that narrow-leafed non-commodity that so many of us farm without tangible reward. [sonofdodie] has a particularly hard row to hoe—his backyard is one big, 30° slope of knee-ruining agony. After 30 years of trudging up and down the hill, his body was telling him to find a better way. But no lawn service would touch it, so he waited for divine inspiration.

And lo, the answer came to [sonofdodie] in a trio of string trimmers. These Whirling Dervishes of grass grazing are mounted on a wheeled plywood base so that their strings overlap slightly for full coverage. Now he can sit in the shade and sip lemonade as he mows via rope and extension cord using a mower that cost about $100 to build.

These heavenly trimmers have been modified to use heavy nylon line, which means they can whip two weeks’ worth of rain-fueled growth with no problem. You can watch the mower shimmy down what looks like the world’s greatest Slip ‘n Slide hill after the break.

Yeah, this video is two years old, but somehow we missed it back then. Ideas this fresh that tackle age-old problems are evergreen, unlike these plots of grass we must maintain. There’s more than one way to skin this ecological cat, and we’ve seen everything from solar mowers to robotic mowers to mowers tied up to wind themselves around a stake like an enthusiastic dog.

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What Is Our Martian Quarantine Protocol?

June 19, 2018 by Al Williams 89 Comments

If you somehow haven’t read or watched War of the Worlds, here’s a spoiler alert. The Martians are brought down by the common cold. You can argue if alien biology would be susceptible to human pathogens, but if they were, it wouldn’t be surprising if aliens had little defense against our bugs. The worrisome part of that is the reverse. Could an astronaut or a space probe bring back something that would ravage the Earth with some disease? This is not science fiction, it is both a historically serious question and one we’ll face in the near future. If we send people to Mars are they going to come back with something harmful?

A Bit of News: Methane Gas Fluctuations on Mars

What got me thinking about this was the mounting evidence that there could be life on Mars. Not a little green man with a death ray, but perhaps microbe-like life forms. In a recent press release, NASA revealed that they not only found old organic material in rocks, but they also found that methane gas is present on Mars and the amount varies based on the season with more methane occurring in the summer months. There’s some dispute about possible inorganic reasons for this, but it is at least possible that the variation is due to increased biological activity during the summer.

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Fatalities Vs False Positives: The Lessons From The Tesla And Uber Crashes

June 18, 2018 by Elliot Williams 175 Comments

In one bad week in March, two people were indirectly killed by automated driving systems. A Tesla vehicle drove into a barrier, killing its driver, and an Uber vehicle hit and killed a pedestrian crossing the street. The National Transportation Safety Board’s preliminary reports on both accidents came out recently, and these bring us as close as we’re going to get to a definitive view of what actually happened. What can we learn from these two crashes?

There is one outstanding factor that makes these two crashes look different on the surface: Tesla’s algorithm misidentified a lane split and actively accelerated into the barrier, while the Uber system eventually correctly identified the cyclist crossing the street and probably had time to stop, but it was disabled. You might say that if the Tesla driver died from trusting the system too much, the Uber fatality arose from trusting the system too little.

But you’d be wrong. The forward-facing radar in the Tesla should have prevented the accident by seeing the barrier and slamming on the brakes, but the Tesla algorithm places more weight on the cameras than the radar. Why? For exactly the same reason that the Uber emergency-braking system was turned off: there are “too many” false positives and the result is that far too often the cars brake needlessly under normal driving circumstances.

The crux of the self-driving at the moment is precisely figuring out when to slam on the brakes and when not. Brake too often, and the passengers are annoyed or the car gets rear-ended. Brake too infrequently, and the consequences can be worse. Indeed, this is the central problem of autonomous vehicle safety, and neither Tesla nor Uber have it figured out yet.

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Opening A Ford With A Robot And The De Bruijn Sequence

June 18, 2018 by Brian Benchoff 72 Comments

The Ford Securicode, or the keyless-entry keypad available on all models of Ford cars and trucks, first appeared on the 1980 Thunderbird. Even though it’s most commonly seen on the higher-end models, it is available as an option on the Fiesta S — the cheapest car Ford sells in the US — for $95. Doug DeMuro loves it. It’s also a lock, and that means it’s ready to be exploited. Surely, someone can build a robot to crack this lock. Turns out, it’s pretty easy.

The electronics and mechanical part of this build are pretty simple. An acrylic frame holds five solenoids over the keypad, and this acrylic frame attaches to the car with magnets. There’s a second large protoboard attached to this acrylic frame loaded up with an Arduino, character display, and a ULN2003 to drive the resistors. So far, everything you would expect for a ‘robot’ that will unlock a car via its keypad.

The real trick for this build is making this electronic lockpick fast and easy to use. This project was inspired by [Samy Kamkar]’s OpenSesame attack for garage door openers. In this project, [Samy] didn’t brute force a code the hard way by sending one code after another; (crappy) garage door openers only look at the last n digits sent from the remote, and there’s no penalty for sending the wrong code. In this case, it’s possible to use a De Bruijn sequence to vastly reduce the time it takes to brute force every code. Instead of testing tens of thousands of different codes sequentially, this robot only needs to test 3125, something that should only take a few minutes.

Right now the creator of this project is putting the finishing touches on this Ford-cracking robot. There was a slight bug in the code that was solved by treating the De Bruijn sequence as circular, but now it’s only a matter of time before a 1993 Ford Taurus wagon becomes even more worthless.

Dissecting The Elusive Wax Motor

June 18, 2018 by Tom Nardi 34 Comments

We’d wager most readers aren’t intimately acquainted with wax motors. In fact, a good deal of you have probably never heard of them, let alone used one in a project. Which isn’t exactly surprising, as they’re very niche and rarely used outside of HVAC systems and some appliances. But they’re fascinating devices, and once you’ve seen how they work, you might just figure out an application for one.

[AvE] recently did a complete teardown on a typical wax motor, going as far as cutting the thing in half to show the inner workings. Now we’ve seen some readers commenting that everyone’s favorite foul-mouthed destroyer of consumer goods has lost his edge, that his newer videos are more about goofing off than anything. Well we can’t necessarily defend his signature linguistic repertoire, but we can confidently say this video does an excellent job of explaining these little-known gadgets.

The short version is that a wax motor, which is really a linear actuator, operates on the principle that wax expands when it melts. If a solid block of wax is placed in a cylinder, it can push on a piston during the phase change from solid to liquid. As the liquid wax resists compression, the wax motor has an exceptionally high output force for such a small device. The downside is, the stroke length is usually rather short: for the one [AvE] demonstrates, it’s on the order of 2 mm.

By turning heat directly into mechanical energy, wax motors are often used to open valves and vents when they’ve reached a specific temperature. The common automotive engine thermostat is a classic example of a wax motor, and they’re commonly found inside of dishwashers as a way to open the soap dispenser at the proper time during the cycle.

This actually isn’t the first time we’ve featured an in-depth look at wax motors, but [AvE] actually cutting this one in half combined with the fact that the video doesn’t look like it was filmed on a 1980’s camera makes it worth revisiting the subject. Who is going to build a wax motor power device for the Power Harvesting Challenge in the 2018 Hackaday Prize?

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